Increased effectiveness of allylamine drug compounds for topical treatment of fungal infections of the skin and skin appendages

ABSTRACT

The invention is an increased effectiveness of allylamine drug compounds for topical treatment of fungal infections of skin and skin appendages. The allylamine active ingredient is prepared in an acidic environment; the acidic environment altering the physiochemical properties of the active ingredient resulting in the active ingredient having a positive charge. The positive charge and enhancers used in the formula allow for increased penetration of the active ingredient through skin and skin appendages. The positively charged active ingredients are either dissolved in the vehicle directly or dissolved in a plurality of beads suspended in the vehicle. The bead structure minimizes the molecular diffusion of the positively charged active ingredient and a catalytic species through the bead structure, thus stabilizes the positively charged active ingredient inside the bead by impeding the interaction of the positively charged active ingredient and the catalytic species, and thereby extending the shelf life of the positively charged active ingredient.

CROSS REFERENCE

This application is a continuation of U.S. application Ser. No.14/977,147, filed on Dec. 21, 2015, which is a continuation of U.S.application Ser. No. 14/504,766, filed on Oct. 2, 2014, which is acontinuation of U.S. application Ser. No. 13/252,796, filed on Oct. 4,2011, which is a continuation of U.S. application Ser. No. 12/012,647,filed on Feb. 5, 2008, which claims the benefit of U.S. ProvisionalApplication No. 60/899,433 filed Feb. 5, 2007. The entire teachings ofthe above-referenced applications are incorporated herein by reference.

FIELD OF INVENTION

The invention is an increased effectiveness of allylamine drug compoundsfor topical treatment of fungal infections of the skin and skinappendages. One embodiment of the invention is the use of terbinafine asthe active ingredient for treating various diseases, such asonychomycosis. For the first time the penetration of the nail bedcorneocytes, either through or around the nail plate, is achieved bytopical application of the present invention.

The increased effectiveness for topical treatment of fungal infectionsof the skin and skin appendages uses an allylamine as the activeingredient. One novel feature of the invention is that the positivelycharged allylamine drug compounds and penetrating enhancers used in theinvention make it effective for topical treatment of fungal infectionsof the skin and skin appendages. The active ingredient is prepared in anacidic environment; the acidic environment altering the physiochemicalproperties of the active ingredient resulting in the active ingredienthaving a positive charge. It is this positive charge and the enhancersused in the formula that allow for increased effectiveness for topicaltreatment of fungal infections of the skin and skin appendages. Thepositively charged active ingredients are either dissolved in a deliveryvehicle directly or dissolved in a plurality of beads suspended in thevehicle. The preferred delivery vehicle is transparent, but alternativedelivery vehicles with various degrees of transparency may be used. Thebead structure minimizes the molecular diffusion of the positivelycharged active ingredient and a catalytic species through the beadstructure, thus stabilizes the positively charged active ingredientinside the bead by impeding the interaction of the positively chargedactive ingredient and the catalytic species, and thereby extending theshelf life of the positively charged active ingredient.

BACKGROUND

A major goal of the pharmaceutical and cosmeceutical industry is thedevelopment of effective products. Topical products are of interestsince they are not invasive, they can be applied directly to the targetarea, and thus have fewer side effects. The development of effectivetopical products needs a multidisciplinary approach since the activeingredients must have optimum solubility, adequate stability and optimumconcentration at the target area. The skin and skin appendages havedifferent structures and compositions, so what is needed is an inventionthat can overcome their hard to penetrate barriers.

Therefore, it is an objective of the present invention to make productsthat are effective for topical treatment of fungal infections of theskin and skin appendages.

SUMMARY

The invention is an increased effectiveness of allylamine drug compoundsfor topical treatment of fungal infections of the skin and skinappendages. Various allylamines can be used as the active ingredient. Anovel feature of the invention is that the positively charged allylaminedrug compounds and penetrating enhancers used in the invention make iteffective for topical treatment of fungal infections of the skin andskin appendages. The active ingredient is prepared in an acidicenvironment; the acidic environment altering the physiochemicalproperties of the active ingredient resulting in the active ingredienthaving a positive charge. It is this positive charge and the enhancersused in the formula that allow for increased effectiveness of allylaminedrug compounds for topical treatment of fungal infections of the skinand skin appendages. The positively charged active ingredients aredissolved in a delivery vehicle directly or may be dissolved in aplurality of beads suspended in the vehicle. The bead structureminimizes the molecular diffusion of the positively charged activeingredient and a catalytic species through the bead structure, thusstabilizes the positively charged active ingredient inside the bead byimpeding the interaction of the positively charged active ingredient andthe catalytic species, and thereby extending the shelf life of thepositively charged active ingredient.

In one preferred embodiment, the active ingredient is an allylamineselected from the group consisting of terbinafine hydrochloride ornaftifine hydrochloride. The active ingredient is dissolved in at leastone solubilizer and the pH of the resulting mixture is adjusted to lessthan 7.5 using a buffer. The active ingredient is deemed to becompletely dissolved in the allylamine/buffer/solubilizer mixture. Theactive ingredient can be added to the buffer first then thesolubilizer(s) is added to completely dissolve the active ingredient orvice versa. In this embodiment, terbinafine hydrochloride is added tothe buffer such that the final concentration of terbinafinehydrochloride in the bead structure is 0.001 to 6% (weight/weight). Thepreferred acidic buffer is a citrate buffer with a pH of less than 7.5.The preferred pH range of the acidic buffer is 3.5 to 6. The preferredcitrate buffer is prepared by mixing citric acid and sodium citrate,however other commonly known acidic buffers may be used. An ultrasonicprobe or other similar means may be used to assist the dissolutionprocess.

In order to completely dissolve the allylamine of the preferredembodiment, at least one solubilizer is used to dissolve the allylamine.In the preferred embodiment, the addition of ethanol was used as thesolubilizer, however other known solubilizers may be used. The activeingredient is deemed to be completely dissolved in theallylamine/buffer/solubilizer mixture.

At least one enhancer is then added to the mixture. The enhancers usedin the preferred embodiment were ethanol, polysorbate 80, phospholipids,propylene glycol and/or 1,3-butanediol. However, other known enhancerssuch as other alcohols, fatty alcohols, fatty acids, fatty acid esters,polyols, amides, pyrrolidone derivatives, surfactants, phospholipids andterpenes may be used in alternative embodiments.

Antioxidants are then added to the above mixture and stirred untildissolved. The antioxidants in the preferred embodiment were used toprotect the active ingredients. The use of antioxidants for stabilizingpreparations is common knowledge in the pharmaceutical industry. Theantioxidants of the present invention are not specifically chosen fortheir antioxidant effect on skin. In the preferred embodiment,alpha-tocopherol, butylated hydroxytoluene and butylated hydroxylanisoleare used as the antioxidants. However, other known antioxidants may beused in alternative embodiments.

Preservatives are then added to the mixture. In the preferredembodiment, methyl 4-hydroxybenzoate and propyl 4-hydroxybenzoate aredissolved in 1,3-butanediol. The preservative mixture is then added tothe allylamine mixture above. In alternative embodiments, other types ofpreservatives may be used.

A humectant is then added to the mixture. The humectants used in thepreferred embodiments are 1,3-butanediol or propylene glycol. However,other known humectants such as glycerin, sorbitol and polyethyleneglycol may be used in alternative embodiments.

A viscosity increasing agent(s) is then added to the mixture. In thepreferred embodiment carbopol 940 and/or hydroxyethyl cellulosedispersed in 1,3-butanediol or propylene glycol is used as the viscosityincreasing agent(s). However, other known gelling agents or viscosityincreasing agents such as other acrylic polymers, cellulose derivatives,natural gums and poloxamers may be used in alternative embodiments.

If needed, other acids or bases commonly used in pharmaceuticalpreparations such as hydrochloric acid, sodium hydroxide and potassiumhydroxide may be used to adjust the final pH to less than 7.5,preferably 3.5 to 6.0.

A delivery vehicle is added and the resulting mixture placed in astorage container for future use or transferred into a dispenser forapplication to skin, skin appendages, and nails.

In a preferred alternate embodiment, a vehicle containing a plurality ofbeads is used. In this embodiment, the invention is prepared aspreviously discussed but sodium alginate is used to increase the mixtureviscosity instead of carbopol 940 and/or hydroxyethyl cellulose. Also,instead of placing the mixture in a storage container or a dispenser,the resulting mixture is then passed through a dispensing tip into ahardening agent. The effect of the interaction between the aliquotedsolution and the hardening agent is to harden the outer most exposedarea of each aliquot to form a bead. In the preferred embodiment, themixture is passed through a dispensing tip having an orifice diameter of0.2-5 millimeters. A plurality of beads is produced by the aliquotedmixture. Although a dispensing tip was used for the preferredembodiment, other commonly known dispensing methods may be used.

Although 0.1-20% calcium chloride solution was used as the hardeningagent in the preferred embodiment other types of hardening agents may beused. The type of hardening agent selected will depend on the polymerused to form the beads. For example, in alginate beads, a divalentcation is usually used, such as calcium ion or barium ion, especiallycalcium chloride and barium chloride.

Each bead preferably measures 2-2.5 millimeters in size. However, thebeads may range from 0.2 to 10 millimeters in size. The bead may benegatively charged due to the negative nature of alginate, although someof the alginate would cross-link with the calcium ions.

The plurality of beads are then sieved and washed with an aqueous buffersolution. In the preferred embodiment, citrate buffer was used to washthe plurality of beads; however, other types of buffer solutions may beused. It is preferable that the citrate buffer has a pH of less than7.5, and preferably has a pH of 3.5 to 6.0. In the alternate preferredembodiment, the plurality of beads is then delivered to a fluidized beddryer by a motor-driven sieve belt. The plurality of beads is dried byvertically blowing them through the fluidized bed dryer or another typeof mechanical delivery and drying method.

The plurality of beads is then transferred to an agitator containing agel base and mixed by a propeller until homogenous. Other gelling agentsmay be used to form the gel base, such as cellulose derivatives andxanthan gum. The resulting bead/gel mixture is then placed in a storagecontainer for future use or placed into a dispensing container forapplication.

In the preferred embodiment, the gel is prepared by dispersing a gellingagent in a humectant. A buffer with a pH of less than 7.5, preferably3.5 to 6.0, is added to the dispersion and stirred until homogeneous.Preservatives are dissolved in the humectant and added to the mixtureand stirred until homogenous.

In the preferred alternate embodiment, the gelling agent(s) used wascarbopol 940 and/or hydroxylethyl cellulose. However, other knowngelling agents or viscosity increasing agents such as other acrylicpolymers, cellulose derivatives, natural gums and poloxamers may be usedin alternative embodiments. The pH of the final gel is preferably 3.5 to6.0 and may be adjusted using other commonly known pH adjustingsolutions such as hydrochloric acid, sodium hydroxide and potassiumhydroxide.

In the preferred and alternate preferred embodiments, the gel acts as adelivery vehicle or base for the beads. The gel also acts as a storagemedium. The base is not critical in the delivery of the activeingredient to the target location. In some embodiments the deliveryvehicle may be transparent while in other embodiments the deliveryvehicle may be opaque or colored. Transparency, opaqueness and color arecharacteristic of the type of vehicle used in the formulation. Forexample, if waxes are used as the vehicle, the vehicle would be white incolor.

Due to the fact that so many beads in the alternate preferred embodimentare contained in the base, the beads are in contact with one another andit is very hard to observe any changes in the base. In fact, the onlyway to determine if active ingredient is diffusing through the bead wallis to analyze the gel using high performance liquid chromatography(HPLC).

DETAILED DESCRIPTION

The invention is an increased effectiveness of allylamine drug compoundsfor topical treatment of fungal infections of the skin and skinappendages. Various allylamines can be used as the active ingredient. Anovel feature of the invention is that the positively charged allylaminedrug compounds and penetrating enhancers used in the invention make iteffective for topical treatment of fungal infections of the skin andskin appendages. The active ingredient is prepared in an acidicenvironment; the acidic environment altering the physiochemicalproperties of the active ingredient resulting in the active ingredienthaving a positive charge. It is this positive charge and the enhancersused in the formula that allow for increased effectiveness of the activeingredient for topical treatment of fungal infections of the skin andskin appendages. The positively charged active ingredients are dissolvedin a delivery vehicle directly or may be dissolved in a plurality ofbeads suspended in the vehicle. The bead structure minimizes themolecular diffusion of the positively charged active ingredient and acatalytic species through the bead structure, thus stabilizes thepositively charged active ingredient inside the bead by impeding theinteraction of the positively charged active ingredient and thecatalytic species, and thereby extending the shelf life of thepositively charged active ingredient.

In the preferred embodiment, the active ingredient is dissolved in atleast one solubilizer and the pH of the resulting mixture is adjusted toless than 7.5 using a buffer. The active ingredient is deemed to becompletely dissolved in the allylamine/buffer/solubilizer mixture. Theactive ingredient can be added to the buffer first then thesolubilizer(s) is added to completely dissolve the active ingredient orvice versa. An ultrasonic probe or other similar means may be used toassist the dissolution process. Antioxidants, enhancers, preservatives,humectants and viscosity increasing agents are then added to themixture.

In an alternate embodiment, a vehicle containing a plurality of beads isused. In this embodiment, the bead structure is prepared by dissolvingthe active ingredient in at least one solubilizer and the pH of mixtureis adjusted to less than 7.5 using a buffer. An ultrasonic probe orother similar means may be used to assist the dissolution process.Antioxidants, enhancers, preservatives and humectants are then added tothe mixture. A viscosity increasing agent dissolved in a solvent isadded to the mixture. The resulting mixture is then passed throughdispensing tips into a hardening agent. As each aliquot of the dispensedmixture encounters the hardening agent a bead is formed. The dispensingstep produces a plurality of beads. The plurality of beads are thensieved and washed with an aqueous buffer solution. The plurality ofbeads is then delivered to a fluidized bed dryer using a motor drivensieve belt. The plurality of beads is then dried by vertically blowingthem through the fluidized bed dryer. The plurality of beads then aretransferred to an agitator containing a gel base and mixed by apropeller until homogenous. The resulting bead/gel mixture is thenplaced in a storage container for future use or placed into a dispensingcontainer for application.

In the preferred embodiment, the active ingredient is an allylamineselected from the group consisting of terbinafine hydrochloride ornaftifine hydrochloride. However, in other embodiments, the activeingredient may be selected from any class of compound that iscommercially available. Terbinafine is a white to off-white finecrystalline powder and has very limited solubility in water (<0.001%).Terbinafine hydrochloride is a white to off-white fine crystallinepowder with a melting point of approximately 205 degrees Celsius. ThepKa value is 7.10 and the pH of a solution (0.5%) in methanol/water(4:6) is approximately 4.7 at 25 degrees Celsius. The solubility ofterbinafine hydrochloride is 0.63% (w/v) in water. Terbinafine intopical preparation in the marketplace (1%) is usually in basic solution(pH >7.5).

In one of the preferred embodiments, the terbinafine hydrochloride isthe allylamine used to make the invention. In this embodiment,terbinafine hydrochloride is added to an acidic buffer such that thefinal concentration of terbinafine hydrochloride in the bead structureis 0.001 to 6% (weight/weight). The preferred acidic buffer is a citratebuffer with a pH of less than 7.5. The preferred pH range of the acidicbuffer is 3.5 to 6. The preferred citrate buffer is prepared by mixingcitric acid and sodium citrate. Although citrate buffer was used in thepreferred embodiment, other commonly known acidic buffer solutions maybe used, such as phosphate buffer or acetate buffer.

In order to completely dissolve the allylamine of the preferredembodiment, at least one solubilizer is used to dissolve the allylamine.In the preferred embodiment, the addition of ethanol was used as thesolubilizer. An ultrasonic probe was used to assist the dissolution ofthe terbinafine hydrochloride. The active ingredient is deemed to becompletely dissolved in the allylamine/buffer/solubilizer mixture.Although ethanol was used in the preferred embodiment, other knownsolubilizers such as other alcohols, glycols, surfactants and complexingagents may be used in alternative embodiments. Furthermore, othercommercially available mechanism may be used to assist the dissolutionof the allylamine.

At least one enhancer is then added to the mixture. The enhancers usedin the preferred embodiment were ethanol, polysorbate 80, phospholipids,propylene glycol and/or 1,3-butanediol. However, other known enhancerssuch as other alcohols, fatty alcohols, fatty acids, fatty acid esters,polyols, amides, pyrrolidone derivatives, surfactants, phospholipids andterpenes may be used in alternative embodiments.

Antioxidants are then added to the above mixture and stirred untildissolved. The antioxidants in the preferred embodiment were used toprotect the active ingredients. The use of antioxidants for stabilizingpreparations is common knowledge in the pharmaceutical industry. Theantioxidants of the present invention are not specifically chosen fortheir antioxidant effect on skin.

In the preferred embodiment, alpha-tocopherol, butylated hydroxytolueneand butylated hydroxylanisole are used as the antioxidants. However,other known antioxidants may be used in alternative embodiments.

Preservatives are then added to the mixture. In the preferredembodiment, methyl 4-hydroxybenzoate and propyl 4-hydroxybenzoate aredissolved in 1,3-butanediol. The preservative mixture is then added tothe allylamine mixture above. In alternative embodiments, other types ofpreservatives may be used.

A humectant is then added to the mixture. The humectants used in thepreferred embodiments are 1,3-butanediol or propylene glycol. However,other known humectants such as glycerin, sorbitol and polyethyleneglycol may be used in alternative embodiments. The humectant promotesthe retention of moisture in the invention.

A viscosity increasing agent(s) is then added to the mixture. In thepreferred embodiment carbopol 940 and/or hydroxyethyl cellulosedispersed in 1,3-butanediol or propylene glycol was used as theviscosity increasing agent(s). However, other known gelling agents orviscosity increasing agents such as acrylic polymers, cellulosederivatives, natural gums and poloxamers may be used in alternativeembodiments.

If needed, other acids or bases commonly used in pharmaceuticalpreparations such as hydrochloric acid, sodium hydroxide and potassiumhydroxide may be used to adjust the final pH to less than 7.5,preferably 3.5 to 6.0.

The procedure for making one embodiment of the invention would be asfollows:

-   1. Dissolve terbinafine HCl in 5-50% ethanol in a closed system to    completely dissolve terbinafine HCl.-   2. Add 18.6-92.3% citrate buffer with a pH of less than 7.5    (preferably 3.5-6.0) in step 1 using an ultrasonic probe.-   3. Add 0.001-0.2% alpha-tocopherol, butylated hydroxytoluene, and    butylated hydroxyl anisole to the mixture and stir until dissolved.-   4. Dissolve 0.1-0.2% methyl 4-hydroxybenzoate and 0.01-0.1% propyl    4-hydroxybenzoate in 0.5-2% 1,3-butanediol and add to the mixture.-   5. Disperse 0.1-2.5% of carbomer 940 in 2.00-20% of 1,3-butanediol.-   6. Add citrate buffer with a pH of less than 7.5 (preferably    3.5-6.0) to the carbomer dispersion in step 5 and stir until    homogeneous.-   7. Add the mixture in step 4 to the carbomer dispersion in step 6    and stir until homogeneous.-   8. Adjust pH of the mixture to less than 7.5 (preferably 3.5-6.0)    using hydrochloric acid or potassium hydroxide solution if needed,    and stir until homogeneous.

In the preferred embodiment described above, the following ingredientswere used:

Terbinafine Hydrochloride 0.001 to 6% active ingredient (±) α-Tocopherol0.001 to 0.2% antioxidant Carbopol 940 0.1 to 2.5% viscosity increasingagent Butylated Hydroxytoluene 0.001 to 0.2% antioxidant ButylatedHydroxyanisole 0.001 to 0.2% antioxidant Methyl 4-Hydroxybenzoate 0.1 to0.2% preservative Propyl 4-Hydroxybenzoate 0.01 to 0.1% preservative1,3-Butanediol 2 to 20% humectant, enhancer Ethanol 5 to 50%Solubilizer, enhancer Citric Acid Monohydrate buffer Sodium Citratebuffer

The citrate buffer is used to make pH of less than 7.5 (preferably3.5-6.0).

In another preferred embodiment, the following ingredients were used:

Terbinafine Hydrochloride 0.001 to 6% active ingredient (±) α-Tocopherol0.001 to 0.2% antioxidant Carbopol 940 0.1 to 2.5% viscosity increasingagent Butylated Hydroxytoluene 0.001 to 0.2% antioxidant ButylatedHydroxyanisole 0.001 to 0.2% antioxidant Methyl 4-Hydroxybenzoate 0.1 to0.2% preservative Propyl 4-Hydroxybenzoate 0.01 to 0.1% preservative1,3-Butanediol 2 to 20% humectant, enhancer Polysorbate 20 1 to 40%Solubilizer, enhancer Citric Acid Monohydrate buffer Sodium Citratebuffer

The citrate buffer is used to make pH of less than 7.5 (preferably3.5-6.0).

In third preferred embodiment, the following ingredients were used:

Terbinafine Hydrochloride 0.001 to 6% active ingredient (±) α-Tocopherol0.001 to 0.2% antioxidant Carbopol 940 0.1 to 2.5% viscosity increasingagent Butylated Hydroxytoluene 0.001 to 0.2% antioxidant ButylatedHydroxyanisole 0.001 to 0.2% antioxidant Methyl 4-Hydroxybenzoate 0.1 to0.2% preservative Propyl 4-Hydroxybenzoate 0.01 to 0.1% preservativePropylene Glycol 2 to 20% humectant, enhancer Polysorbate 80 1 to 40%Solubilizer, enhancer Citric Acid Monohydrate buffer Sodium Citratebuffer

The citrate buffer is used to make pH of less than 7.5 (preferably3.5-6.0).

In a fourth preferred embodiment, the following ingredients were used:

Terbinafine Hydrochloride 0.001 to 6% active ingredient (±) α-Tocopherol0.001 to 0.2% antioxidant Carbopol 940 0.1 to 2.5% viscosity increasingagent Hydroxyethyl cellulose 0.1 to 6% viscosity increasing agentButylated Hydroxytoluene 0.001 to 0.2% antioxidant ButylatedHydroxyanisole 0.001 to 0.2% antioxidant Methyl 4-Hydroxybenzoate 0.1 to0.2% preservative Propyl 4-Hydroxybenzoate 0.01 to 0.1% preservative1,3-Butanediol 2 to 20% humectant, enhancer Ethanol 5 to 50%solubilizer, enhancer Phospholipids 1 to 20% solubilizer, enhancerCitric Acid Monohydrate buffer Sodium Citrate buffer

The citrate buffer is used to make pH of less than 7.5 (preferably3.5-6.0).

In a fifth preferred embodiment, the following ingredients were used:

Terbinafine Hydrochloride 0.001 to 6% active ingredient (±) α-Tocopherol0.001 to 0.2% antioxidant Carbopol 940 0.1 to 2.5% viscosity increasingagent Butylated Hydroxytoluene 0.001 to 0.2% antioxidant ButylatedHydroxyanisole 0.001 to 0.2% antioxidant Methyl 4-Hydroxybenzoate 0.1 to0.2% preservative Propyl 4-Hydroxybenzoate 0.01 to 0.1% preservativePropylene Glycol 2 to 20% humectant, enhancer Cholesterol 1 to 25%stabilizer Polysorbate 80 1 to 40% Solubilizer, enhancer Citric AcidMonohydrate buffer Sodium Citrate buffer

The citrate buffer is used to make pH of less than 7.5 (preferably3.5-6.0).

In an alternate embodiment of the preferred invention, a vehiclecontaining a plurality of beads is used to make the invention. In thispreferred embodiment, the bead structure is prepared by dissolving theactive ingredient in a solubilizer and the pH of resulting mixture isadjusted to less than 7.5 using a buffer. An ultrasonic probe or othersimilar means may be used to assist the dissolution process.Antioxidants, enhancers, preservatives and humectants are then added tothe mixture using the same procedure as the preferred embodimentspreviously described. A viscosity increasing agent is then added to themixture. The viscosity increasing agent used in the this embodiment wassodium alginate dispersed in 1,3-butanediol. However, other knownviscosity increasing agents may be used in alternative embodiments.

The resulting mixture is then passed through a dispensing tip into ahardening agent. The effect of the interaction between the aliquotedsolution and the hardening agent is to harden the outer most exposedarea of each aliquot to form a bead. In the preferred embodiment, themixture is passed through a dispensing tip having an orifice diameter of0.2-5 millimeters. A plurality of beads is produced by the aliquotedmixture. Although a dispensing tip was used for the preferredembodiment, other commonly known dispensing methods may be used.

In the preferred alternate embodiment, a 0.1-20% calcium chloridesolution was used as the hardening agent. Other types of hardeningagents may be used. The type of hardening agent selected will depend onthe polymer used to form the beads. For example, in alginate beads, adivalent cation is usually used, such as calcium ion or barium ion,especially calcium chloride and barium chloride.

In the alternate preferred embodiment, each bead measures 2-2.5millimeters in size. However, the beads may range from 0.2 to 10millimeters in size. The bead may be negatively charged due to thenegative nature of alginate, although some of the alginate wouldcross-link with the calcium ions. The applicants have not yet performedany experiments to determine cross-linking density and drug releaserates through the bead shell.

The plurality of beads are then sieved and washed with an aqueous buffersolution. In the preferred embodiment, citrate buffer was used to washthe plurality of beads. It is preferable that the citrate buffer has apH of less than 7.5, and preferably has a pH of 3.5 to 6.0. Inalternative embodiments, other types of buffer solutions may be used. Inthe alternate preferred embodiment, the plurality of beads is thendelivered to a fluidized bed dryer by a motor-driven sieve belt. Theplurality of beads is dried by vertically blowing them through thefluidized bed dryer. Although a motor-driven sieve belt and a fluidizedbed dryer were used in the preferred embodiment, other types ofmechanical delivery and drying methods may be used.

The plurality of beads is then transferred to an agitator containing agel base and mixed by a propeller until homogenous. Other gelling agentsmay be used to form the gel base, such as cellulose derivatives andxanthan gum. The resulting bead/gel mixture is then placed in a storagecontainer for future use or placed into a dispensing container forapplication.

In the preferred embodiment, the gel is prepared by dispersing a gellingagent in a humectant. A buffer with a pH of less than 7.5, preferably3.5 to 6.0, is added to the dispersion and stirred until homogeneous.Preservatives are dissolved in the humectant and added to the mixtureand stirred until homogenous.

In the preferred alternate embodiment, the gelling agent(s) used wascarbopol 940 and/or hydroxylethyl cellulose. However, other knowngelling agents or viscosity increasing agents such as acrylic polymers,cellulose derivatives, natural gums and poloxamers may be used inalternative embodiments. The pH of the final gel is preferably 3.5 to6.0 and may be adjusted using other commonly known pH adjustingsolutions such as hydrochloric acid, sodium hydroxide and potassiumhydroxide.

In the preferred and alternate embodiments, the gel acts as a deliveryvehicle or base for the beads. The gel also acts as a storage medium.The base is not critical in the delivery of the active ingredient to thetarget location. In some embodiments the delivery vehicle may betransparent while in other embodiments the delivery vehicle may beopaque or colored. Transparency, opaqueness and color are characteristicof the type of vehicle used in the formulation. For example, if waxesare used as the vehicle, the vehicle would be white in color.

Due to the fact that so many beads in the alternate preferred embodimentare contained in, the base, the beads are in contact with one anotherand it is very hard to observe any changes in the base. In fact, theonly way to determine if active ingredient is diffusing through the beadwall is to analyze the gel using high performance liquid chromatography(HPLC).

The procedure for making one alternate embodiment of the invention'sbeads would be as follows:

-   1. Dissolve terbinafine HCl in 5-50% ethanol in a closed system to    completely dissolve terbinafine HCl.-   2. Add 18.6-92.3% citrate buffer with a pH of less than 7.5    (preferably 3.5-6.0) in step 1 using an ultrasonic probe.-   3. Add 0.001-0.2% alpha-tocopherol, butylated hydroxytoluene, and    butylated hydroxylanisole to the mixture and stir until dissolved.-   4. Dissolve 0.1-0.2% methyl 4-hydroxybenzoate and 0.01-0.1% propyl    4-hydroxybenzoate in 0.5-2% 1,3-butanediol and add to the mixture.-   5. Disperse 0.5 to 2.0% sodium alginate in 2-10% 1,3-butanediol and    add to the mixture.-   6. Pass the mixture through tips with a diameter of 0.2-5 mm to    0.1-20% calcium chloride solution and beads are formed.-   7. Sieve the beads and wash them using citrate buffer with a pH of    less than 7.5 (preferably 3.5-6.0).-   8. Deliver the beads using a sieve belt driven by a motor to a    fluidized bed dryer and dry them by vertically blowing them through    the fluidized bed dryer.-   9. Transfer the beads to an agitator containing carbopol gel and mix    them using a propeller until homogeneous.

A step by step procedure of making one embodiment of the invention's gelbase is as follows:

-   1. Disperse 0.1-2.5% of carbomer 940 in 2.00-20% of 1,3-butanediol.-   2. Add citrate buffer with a pH of less than 7.5 (preferably    3.5-6.0) to the carbomer dispersion and stir until homogeneous.-   3. Dissolve 0.1-0.2% methyl 4-hydroxybenzoate and 0.01-0.1% propyl    4-hydroxybenzoate in 0.5-2% 1,3-butanediol and add to the mixture.-   4. Adjust pH of the mixture to less than 7.5 (preferably 3.5-6.0)    using hydrochloric acid or potassium hydroxide solution if needed,    and stir until homogeneous.

The following data, obtained during development of the invention, showsterbinafine hydrochloride amount (mg) in each bead normalized to aweight of 0.0073 grams per bead (average weight of 10 beads). Theaverage amount of terbinafine HCl per bead is 0.095±0.004 mg.

Bead No. 1 2 3 4 5 6 7 8 9 10 Bead 0.0085 0.0075 0.0070 0.0071 0.00820.0065 0.0067 0.0067 0.0075 0.0073 Weight (g) Terbinafine 0.091 0.0960.093 0.095 0.093 0.098 0.090 0.104 0.097 0.095 HCl (mg) per bead

Each bead is a protective envelop which is designed to extend the shelflife of the positively charged active ingredient contained within eachindividual bead. In the preferred alternate embodiment, the beadstructure is more like a solid than an aqueous gel base. Therefore it isdifficult for the molecules inside the beads to diffuse and react. Thusthe bead structure helps stabilize the ingredients inside.

As long as the bead is in the delivery vehicle, the bead retains andlimits the active ingredient to enter the delivery vehicle. This allowsthe use of a bead and the delivery vehicle to form combinationsdesirable for other ingredients which may be interactive in regularvehicles.

Analysis of one preferred embodiment shows the bead structure helpsstabilize the ingredients inside. When using terbinafine hydrochlorideas the active ingredient, it has been shown that the predictedshelf-life of terbinafine hydrochloride as used in the present inventionis greater when compared to terbinafine hydrochloride in gel alone(without the bead structure of the present invention).

Terbinafine HCl concentration (g %) Gel time (stored at ambient Beads inGel (days) temperature) (stored at 30° C.) 0 1.0922 1.0411 1.0029 0.94370.9752 0.9967 11 1.0131 1.0144 39 1.0542 1.0540 1.0199 41 1.0655 0.92500.9566 68 0.9790 0.9731 1.0214 70 1.0449 0.9741 1.0200 253 0.975 0.9583

By extrapolating the zero order kinetics of the data above (Terbinafineconcentration (g %)=−0.000195 time (days)+1.0158), the predictedshelf-life of terbinafine in gel is 532 days, while the zero orderkinetics of terbinafine beads in gel (Terbinafine concentration (g%)=−0.000091 time (days)+1.0111) gives the predicted shelf-life of 1134days.

In prototype development, the composition of each bead was soprotective, that the allylamine terbinafine hydrochloride was retainedin bead. Analysis of prototype samples was conducted during developmentfound the amount of terbinafine HCl leaking from the beads to be 0.27%,4.25%, and 6.37% of terbinafine HCl in gel base after 1, 46, and 84days, respectively.

In the preferred alternate embodiment, the following ingredients wereused to make the present invention:

Terbinafine hydrochloride 0.001 to 6% active ingredient (±) α-Tocopherol0.001 to 0.2% antioxidant Sodium Alginate 0.5 to 2.0% viscosityincreasing agent Carbopol 940 0.1 to 2.5% viscosity increasing agentButylated Hydroxytoluene 0.001 to 0.2% antioxidant ButylatedHydroxyanisole 0.001 to 0.2% antioxidant Methyl 4-Hydroxybenzoate 0.1 to0.2% preservative Propyl 4-Hydroxybenzoate 0.01 to 0.1% preservative1,3-Butanediol 2 to 20% humectant, enhancer Ethanol 5 to 50%solubilizer, enhancer Citric Acid Monohydrate buffer Sodium Citratebuffer

The citrate buffer is used to make pH of less than 7.5 (preferably3.5-6.0).

In another of the preferred alternate embodiment, the followingingredients were used:

Terbinafine hydrochloride 0.001 to 6% active ingredient (±) α-Tocopherol0.001 to 0.2% antioxidant Sodium Alginate 0.5 to 2.0% viscosityincreasing agent Carbopol 940 0.1 to 2.5% viscosity increasing agentButylated Hydroxytoluene 0.001 to 0.2% antioxidant ButylatedHydroxyanisole 0.001 to 0.2% antioxidant Methyl 4-Hydroxybenzoate 0.1 to0.2% preservative Propyl 4-Hydroxybenzoate 0.01 to 0.1% preservative1,3-Butanediol 2 to 20% humectant, enhancer Ethanol 5 to 50%solubilizer, enhancer Phospholipids 1 to 20% solubilizer, enhancerCitric Acid Monohydrate buffer Sodium Citrate buffer

The citrate buffer is used to make pH of less than 7.5 (preferably3.5-6.0).

In a third preferred alternate embodiment, the following ingredientswere used:

Terbinafine hydrochloride 0.001 to 6% active ingredient (±) α-Tocopherol0.001 to 0.2% antioxidant Sodium Alginate 0.5 to 2.0% viscosityincreasing agent Carbopol 940 0.1 to 2.5% viscosity increasing agentButylated Hydroxytoluene 0.001 to 0.2% antioxidant ButylatedHydroxyanisole 0.001 to 0.2% antioxidant Methyl 4-Hydroxybenzoate 0.1 to0.2% preservative Propyl 4-Hydroxybenzoate 0.01 to 0.1% preservativePropylene Glycol 2 to 20% humectant, enhancer Cholesterol 1 to 25%stabilizer Polysorbate 80 1 to 40% solubilizer, enhancer Citric AcidMonohydrate buffer Sodium Citrate buffer

The citrate buffer is used to make pH of less than 7.5 (preferably3.5-6.0).

Although the embodiments are preferably made from the ingredients listedabove, other alternative ingredients may also be used. These alternativeingredients include but are not limited to allylamine drugs as theactive ingredient; alcohols, polyols, surfactants, complexing agents andothers as the solubilizer; alcohols, fatty alcohols, fatty acids, fattyacid esters, polyols, amides, pyrrolidone derivatives, surfactants,phospholipids, terpenes and others as the enhancer; tocopherols,butylated hydroxytoluene, butylated hydroxyanisole, propyl gallate,sodium metabisulfite, sodium bisulfite and ascorbic acid and others asthe antioxidant; EDTA, citric acid and others as the chelating agent;xanthan, alginate, carrageenan, cellulose derivatives, agar or othernatural gums and others as the viscosity increasing agent; other typesof preservatives besides methyl 4-hydroxybenzoate and propyl4-hydroxybenzoate; 1,3-butanediol, propylene glycol, glycerin, sorbitol,polyethylene glycol and others as the humectants; and citric buffer,phosphate buffer, acetate buffer and others as the buffers.

There are other chemicals in each category of the ingredients. Someexamples are:

-   Antioxidants: alkyl gallates such as propyl gallate, ascorbic acid,    sodium sulfite, sodium bisulfite, sodium metabisulfite,    alpha-tocopherols, butylated hydroxytoluene, butylated    hydroxyanisole.-   Chelating agent: citric acid, disodium EDTA, tetrasodium EDTA.-   Humectants: glycerin, propylene glycol, 1,3-butylene glycol,    sorbitol, lactic acid, methyl gluceth-10, aloe vera extract, sodium    PCA, urea, polyethylene glycol 400.-   Anti-freezing agents: ethanol, propylene glycol, polyethylene glycol    400, glycerin, sorbitol.-   Solubilizers: surfactants such as those in the group of Tween, Span,    Poloxamer, Brij, Cremophor; alcohols such as ethanol, isopropyl    alcohol; polyols such as butylene glycol, propylene glycol,    glycerin, sorbitol, low molecular weight polyethylene glycol;    complexing agents such as cyclodextrins.-   Enhancers: alcohols and alkanols such as ethanol, isopropyl alcohol,    decanol; fatty alcohols such as caprylic alcohol, cetyl alcohol,    stearyl alcohol; fatty acids such as oleic acid, caproic acid,    capric acid, lauric acid, myristic acid, stearic acid, caprylic    acid, isostearic acid, polyunsaturated linoleic acid,    alpha-linolenic acid, arachidonic acid; fatty acid esters such as    isopropyl myristate, isopropyl palmitate, isnonyl isononanoate,    ethyl acetate; polyols such as propylene glycol, polyethylene    glycol, glycerol, 1,3-butanediol, sorbitol; terpenes such as    cineole, menthone, limonene, nerolidol, pinene, terpine, menthone,    carvone; amides such as urea, dimethylformamide, cyclic amides such    as 1-dodecylazacycloheptane-2-one (Azone) and its analogues;    pyrrolidone derivatives such as 2-pyrrolidone; essential oils such    as eucalyptus, chenopodium; phospholipids such as    phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine,    phosphatidylinositol, lecithin; surfactants such as sodium lauryl    sulfate, sodium palmitate, sulfosuccinates, cetrimonium bromide,    alkyl betaines, fatty amine sulfates, difatty alkyl triethanolamine    derivatives, sodium lauraminopropionate, acylamphoacetate,    aminopropyl alkylglutamide, lanolin alcohols, polyoxyethylene alkyl    phenols, polyoxyethylene fatty amine, polyoxyethylene fatty alcohol    ether, polyoxyethylene fatty acid esters, sorbitan esters, glyceryl    esters, polysorbates, poloxamers, polyoxythylene glycol monoethers,    cetyltrimethyl ammonium bromide, benzalkonium chloride,    cetylpyridinium chloride; organic acids such as salicylic acid,    salicylates, citric acid.-   Preservatives: methyl 4-hydroxybenzoate, propyl 4-hydroxybenzoate,    benzoic acid.-   Buffers: citric buffer, phosphate buffer, acetate buffer, carbonate    buffer, boric buffer.-   Viscosity increasing agents: natural sources such as acacia,    tragacanth, agar, alginagte, sodium alginate, gellan, gelatin,    carrageenan, pectin, xanthan, chitosan; cellulose derivatives such    as carboxymethylcellulose sodium, ethylcellulose,    hydroxyethylcellulose, methylcellulose,    hydroxypropylmethylcellulose; polyethyenes; acrylic polymers such as    carbomer or carbopol and its derivatives; polyvinylpyrrolidone;    polyvinyl derivatives such as polyvinyl alcohol, polyvinyl acetate;    block copolymers such as poloxamer; colloidally dispersed solids    such as bentonite, hectorite, magnesium aluminum silicate (veegum),    microcrystalline silica, colloidal silicon dioxide, montmorillonite    clay; fatty alcohol such as cetyl alcohol, cetearyl alcohol, stearyl    alcohol, behenyl alcohol; fatty acid such as stearic acid; waxes    such as beeswax, carnauba wax, microcrystalline wax.

In the preferred embodiment of the present invention, the activeingredient is prepared in an acidic environment which alters thephysicochemical properties of the active ingredient resulting in apositive charge. This positive charge and the enhancers used provide theincreased effectiveness of active ingredient for topical treatment offungal infections of the skin and skin appendages. In one preferredembodiment using terbinafine, prototype development revealed positivecharge.

The positive charge can be determined by examining the pKa of the activeingredient. For example, the pKa of terbinafine is 7.10. Theoreticallyat a pH of 7.10, there are 50% positively charged terbinafine moleculesand 50% unionized terbinafine molecules. At pH<pKa, the positivelycharged terbinafine is more than 50%. When pH>pKa the positively chargedterbinafine is less than 50%. At pH of 5.10, there should be about 99%positively charged terbinafine and about 1% unionized terbinafine. Onthe other hand, at pH of 9.10, there should be about 99% unionizedterbinafine and about 1% positively charged terbinafine.

Prototype measurements of zeta potential of the 0.02 g/ml terbinafinehydrochloride solution and the result is positive at pH of below 5.11.However, there are other anions in the solution, e.g., chloride ion andhydroxide ion (sodium hydroxide was used to adjust the solution pH) thatmake negative values of zeta potential.

pH 3.68 5.11 7.07 8.73 Zeta Potential (mV) +12.1 +31.2 −34.0 −58.8

In the preferred embodiment, the invention is applied to the skin orskin appendages including hair and nails through a dispenser and spreadevenly over the treatment area. As the present invention is applied, thebeads are ruptured by the orifice of the dispenser. In alternateembodiments, the orifice of the dispenser may be larger than the beads,thus the beads are ruptured by hand pressure during application. Thedispenser may be a pump, tube or any commercially available containersuitable for such use. No special application tool is needed.

In alternate embodiments the positively charged active ingredient plusenhancers are:

-   -   a. dissolved directly in (or incorporated directly to) the        vehicle. This includes all conventional dosage forms such as        creams, gels, ointments, lotions, emulsions, solutions,        suspensions and pastes.    -   b. entrapped (or encapsulated) in microparticles or        nanoparticles (such as microcapsules, microspheres, liposomes,        microsponges) with diameter size range of 10 nanometers to 200        micrometers.    -   c. entrapped in beads (0.2-10 millimeters)    -   d. entrapped in microparticles or nanoparticles and then further        entrapped in beads (0.2-10 millimeters)

The present invention can be applied to a corneocyte of skin, atrichocyte of hair and an onychocyte of a nail plate and corneocytes ofthe nail bed.

The preferred embodiments described herein are illustrative only, andalthough the examples given include much specificity, they are intendedas illustrative of only a few possible embodiments of the invention.Other embodiments and modifications will, no doubt, occur to thoseskilled in the art. The examples given should be interpreted asillustrations of some of the preferred embodiments of the invention.

What is claimed is:
 1. A method for topical treatment of onychomycosisin a subject in need thereof, wherein the method comprises applying to anail of the subject a composition comprising: (i) a positively chargedterbinafine active ingredient and a penetrating enhancer entrapped in abead structure or in microparticles or nanoparticles, wherein themicroparticles or nanoparticles have a diameter size range of 10nanometers to 200 micrometers, and wherein the enhancer is selected fromthe group consisting of alcohols and alkanols, fatty alcohols, fattyacids, fatty acid esters, polyols, terpenes, amides, cyclic amides,pyrrolidone derivatives, essential oils, phospholipids and surfactants,and (ii) a delivery vehicle, wherein the bead structure or themicroparticles or the nanoparticles are suspended in the deliveryvehicle.
 2. The method of claim 1, wherein the microparticles ornanoparticles are microcapsules, microspheres, liposomes, ormicrosponges.
 3. The method of claim 1, wherein the beads have adiameter size range of 0.2-10 millimeters.
 4. The method of claim 1,wherein the positively charged active ingredient and the enhancer areentrapped in microparticles or nanoparticles which are further entrappedin beads having a diameter size range of 0.2-10 millimeters.
 5. Themethod of claim 1, wherein the positively charged terbinafine activeingredient is terbinafine hydrochloride.
 6. The method of claim 1,wherein the composition comprises about 0.001% to 6% Weight/Weight ofthe positively charged terbinafine active ingredient.
 7. The method ofclaim 1, wherein the composition comprises about 1% to 6% Weight/Weightof the positively charged terbinafine active ingredient.
 8. The methodof claim 1, wherein the composition comprises about 1% Weight/Weight ofthe positively charged terbinafine active ingredient.